INTERACTION PLOT

INTERACTION PLOT

Graphics Command

Given a response variable, Y, and k factor variables, X1 through Xk, it generates a plot of
Y versus X1*X2* ... *Xk

The primary application of this plot is in the design of experiments. Specifically, for 2-level designs where each factor variable is assigned a value of either -1 or +1. A plot of Y versus X1*X2 can then show the 2-term interaction effect.

When there are more than two factor variables, then all the pairwise combinations of the factor variables can be used with the INTERACTION PLOT. This shows all the 2-term interaction effects. This type of plot is referred to as a DEX INTERACTION PLOT. This is in fact the most common use of this command (i.e., the INTERACTION PLOT command is used to generate a DEX INTERACTION PLOT). For example, a MEAN DEX INTERACTION PLOT with five factor variables can be generated with the following commands:

CHARACTER X
LINE BLANK
SET MATRIX PLOT TYPE MEAN DEX INTERACTION
MATRIX PLOT Y X1 X2 X3 X4 X5


Enter HELP SCATTER PLOT MATRIX for the details.

There are two variations of this command. In the first, the raw data for Y is plotted. In the second, a statistic for the distinct values of X1*X2*...*Xk is plotted.

INTERACTION PLOT <y> <x1 ... xk>             <SUBSET/EXCEPT/FOR qualification>
where <y> is the response (= dependent) variable;
            <x1 ... xk> is a list of from 1 to k factor (=independent variables);
and where the <SUBSET/EXCEPT/FOR qualification> is optional.

This syntax is used to plot the raw data for <y>.

<stat> INTERACTION PLOT <y> <x1 ... xk>
                        <SUBSET/EXCEPT/FOR qualification>
where <stat> is one of the following statistics:
MEAN, MIDMEAN, MEDIAN, TRIMMED MEAN, WINDSORIZED MEAN, GEOMETRIC MEAN, HARMONIC MEAN,
SUM, PRODUCT, SIZE (or NUMBER or SIZE),
STANDARD DEVIATION, STANDARD DEVIATION OF MEAN, AVERAGE ABSOLUTE DEVIATION (or AAD), MEDIAN ABSOLUTE DEVIATION (or MAD), VARIANCE, VARIANCE OF THE MEAN, RELATIVE STANDARD DEVIATION, RELATIVE VARIANCE (or COEFFICIENT OF VARIATION),
RANGE, MIDRANGE, MAXIMUM, MINIMUM, EXTREME, LOWER HINGE, UPPER HINGE, LOWER QUARTILE, UPPER QUARTILE,
<FIRST/SECOND/THIRD/FOURTH/FIFTH/SIXTH/ SEVENTH/EIGHTH/ NINTH/TENTH> DECILE,
SKEWNESS, KURTOSIS, NORMAL PPCC,
AUTOCORRELATION, AUTOCOVARIANCE, SINE FREQUENCY, SINE AMPLITUDE,
CP, CPK, EXPECTED LOSS, PERCENT DEFECTIVE,
TAGUCHI SN0 (or SN), TAGUCHI SN+ (or SNL), TAGUCHI SN- (or SNS), TAGUCHI SN00 (or SN2);

            <y> is the response (= dependent) variable;
            <x1 ... xk> is a list of from 1 to k factor (=independent variables);
and where the <SUBSET/EXCEPT/FOR qualification> is optional.

This syntax is used for statistics that require a single variable to compute.

<stat> INTERACTION PLOT <y1> <y2> <x1 ... xk> <SUBSET/EXCEPT/FOR qualification>
where <stat> is one of the following statistics:
LINEAR INTERCEPT, LINEAR SLOPE, LINEAR RESSD, LINEAR CORRELATION, CORRELATION, RANK CORRELATION, COVARIANCE, RANK COVARIANCE,
<y1> is the first response (= dependent) variable;
<y2> is the second response (= dependent) variable;
<x1 ... xk> is a list of from 1 to k factor (=independent variables);
and where the <SUBSET/EXCEPT/FOR qualification> is optional.

This syntax is used for satatistics that require two variables to compute. If a linear fit is performed, the first variable is the dependent variable while the second variable is the independent variable.

INTERACTION PLOT Y X1 X2
MEAN INTERACTION PLOT Y X1 X2
STANDARD DEVIATION INTERACTION PLOT Y X1 X2

None

None

CHARACTERS	= Sets the type for plot characters.
LINES	= Sets the type for plot lines.
STATISTIC PLOT	= Generates a statistic versus subsample plot.
SCATTER PLOT MATRIX	= Generates a scatter plot matrix (including a DEX INTERACTION PLOT).
PLOT	= Generates a data or function plot.

Design of Experiments

2000/1

skip 25
read boxbike2.dat y x1 to x7
.
xtic offset 0.2 0.2
ytic offset 2 2
char x
line blank
y1label y
xlimtis -1 1
major xtic mark number 2
minor xtic mark number
title automatic
.
interaction plot y x1 x2




mean interaction plot y x1 x2




.
title
multiplot scale factor 2
set scatter plot matrix plot type dex interaction
matrix plot y x1 x2 x3 x4 x5 x6 x7